Is there a WD or Seagate 1+TB that doesn't need an external power source?

Do WD or Seagate (or any one for that matter) make a 1TB+ external drive that uses Firewire, but that DOES NOT need to be plugged in? I live off the grid, using solar, so to use the computer and only have ONE appliance plugged in seems easier. is this possible?

Use a Mercury Elite Pro Mini from OWC. It is FW800 and draws its power from the computer. You would still need power to the computer - do not know if there would be enough power running a laptop from battery to also run the external hard drive.